Many atmospheric turbulence deblurring techniques estimate an inverse filter by making assumptions that constrain the mathematical spaces in which an unknown signal and convolving function must reside. Restoration of scene content after imaging through terrestrial imaging paths is an area of active experimentation and development for both real-time feature extraction and post-process data reduction. Static scenes present opportunities for algorithms that exploit the temporal diversity of the atmospheric path since motion of scene content at the image plane over multiple frames may be attributed to a randomly varying blur kernel. This allows for the estimation of inverse filters that can be used to deblur the image. However, when objects in the scene move relative to one another across multiple image frames it complicates an already computationally demanding process. Techniques to compensate for the motion of one or more features can be used, but if the image fidelity is insufficient to detect a moving feature in the first place or the number of features (e.g. fragmentation from an impact or explosion) is very large, motion compensation techniques may break down or become impractical. In this paper we explore using multiple, synchronized optical systems with sufficient spatial separation to provide the optical path turbulence diversity required by many deblurring algorithms. This reduces or eliminates many constraints on object motion when performing reconstructions. We present deblurred imagery examples from an experimental setup that leverages spatially diverse, optical path turbulence and compare the results with the traditional approach of utilizing single path, temporal diversity when performing image reconstructions. Our results demonstrate that: (1) useful deblurring is possible with a single “set” of images simultaneously collected through diverse optical paths, (2) a combination of temporal and spatial diversity of image collection can be a useful “hybrid” approach, and (3) opportunistic weighting of concurrent frames according to image quality can enhance the deblurring results.
This paper describes instrumentation used to adapt the Dunn Solar Telescope (DST) located on Sacramento Peak in Sunspot, NM for observations using the Doppler Spectro Imager (DSI). The DSI is based on a Mach-Zehnder interferometer and measures the Doppler shift of solar lines allowing for the study of atmospheric dynamics of giant planets and the detection of their acoustic oscillations. The instrumentation is being designed and built through a collaborative effort between a French team from the Observatoire de la Cote d’Azur (OCA) that designed the DSI and a US team at New Mexico State University (NMSU). There are four major components that couple the DSI to the DST: a guider/tracker, fast steering mirror (FSM), pupil stabilizer and transfer optics. The guider/tracker processes digital video to centroid-track the planet and outputs voltages to the DST’s heliostat controls. The FSM removes wavefront tip/tilt components primarily due to turbulence and the pupil stabilizer removes any slow pupil “wander” introduced by the telescope’s heliostat/turret arrangement. The light received at a science port of the DST is sent through the correction and stabilization components and into the DSI. The FSM and transfer optics designs are being provided by the OCA team and serve much the same functions as they do for other telescopes at which DSI observations have been conducted. The pupil stabilization and guider are new and are required to address characteristics of the DST.
An approach is presented for numerically simulating incoherent imaging using coherent wave optics propagation methods. The approach employs averaging of irradiance from uncorrelated coherent waves to produce incoherent results. Novel aspects of the method include 1) the exploitation of a spatial windowing feature in the wave optics numerical propagator to limit the angular spread of the light and 2) a simple propagation scaling concept to avoid aliased field components after the focusing element. Classical linear systems theory is commonly used to simulate incoherent imaging when it is possible to incorporate aberrations and/or propagation medium characteristics into an optical transfer function (OTF). However, the technique presented here is useful for investigating situations such as “instantaneous” short-exposure imaging through distributed turbulence and phenomena like anisoplanatism that are not easily modeled with the typical linear systems theory. The relationships between simulation variables such as spatial sampling, source and aperture support, and intermediate focal plane are discussed and the requirement or benefits of choosing these in certain ways are demonstrated.